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    <ul class="crumbs"><li><a href="../index.html">Home</a></li><li><a href="../intern.html">Inter Modules</a></li><li><a href="index.html">pipeline</a></li><li><a href="index.html#2">Chapter 2: Pipelines</a></li><li><b>Read, Move, Stop Stages</b></li></ul></div>
<p class="purpose">Four simple pipeline stages.</p>

<ul class="toc"><li><a href="2-rmss.html#SP2">&#167;2. Read</a></li><li><a href="2-rmss.html#SP3">&#167;3. Move</a></li><li><a href="2-rmss.html#SP4">&#167;4. Stop</a></li></ul><hr class="tocbar">

<p class="commentary firstcommentary"><a id="SP1" class="paragraph-anchor"></a><b>&#167;1. </b></p>

<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">SimpleStages::create_pipeline_stages</span><button class="popup" onclick="togglePopup('usagePopup1')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup1">Usage of <span class="code-font"><span class="function-syntax">SimpleStages::create_pipeline_stages</span></span>:<br/>Parsing Pipelines - <a href="2-pp.html#SP10">&#167;10</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">void</span><span class="plain-syntax">) {</span>
<span class="plain-syntax">    </span><a href="2-pp.html#SP3" class="function-link"><span class="function-syntax">ParsingPipelines::new_stage</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="string-syntax">"stop"</span><span class="plain-syntax">, </span><a href="2-rmss.html#SP4" class="function-link"><span class="function-syntax">SimpleStages::run_stop_stage</span></a><span class="plain-syntax">, </span><span class="constant-syntax">NO_STAGE_ARG</span><span class="plain-syntax">, </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><a href="2-pp.html#SP3" class="function-link"><span class="function-syntax">ParsingPipelines::new_stage</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="string-syntax">"read"</span><span class="plain-syntax">, </span><a href="2-rmss.html#SP2" class="function-link"><span class="function-syntax">SimpleStages::run_read_stage</span></a><span class="plain-syntax">, </span><span class="constant-syntax">FILE_STAGE_ARG</span><span class="plain-syntax">, </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><a href="2-pp.html#SP3" class="function-link"><span class="function-syntax">ParsingPipelines::new_stage</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="string-syntax">"move"</span><span class="plain-syntax">, </span><a href="2-rmss.html#SP3" class="function-link"><span class="function-syntax">SimpleStages::run_move_stage</span></a><span class="plain-syntax">, </span><span class="constant-syntax">GENERAL_STAGE_ARG</span><span class="plain-syntax">, </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">);</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP2" class="paragraph-anchor"></a><b>&#167;2. Read.</b></p>

<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="function-syntax">SimpleStages::run_read_stage</span><button class="popup" onclick="togglePopup('usagePopup2')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup2">Usage of <span class="code-font"><span class="function-syntax">SimpleStages::run_read_stage</span></span>:<br/><a href="2-rmss.html#SP1">&#167;1</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">pipeline_step</span><span class="plain-syntax"> *</span><span class="identifier-syntax">step</span><span class="plain-syntax">) {</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">filename</span><span class="plain-syntax"> *</span><span class="identifier-syntax">F</span><span class="plain-syntax"> = </span><span class="identifier-syntax">step</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">ephemera</span><span class="plain-syntax">.</span><span class="element-syntax">parsed_filename</span><span class="plain-syntax">;</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">BinaryInter::test_file</span><span class="plain-syntax">(</span><span class="identifier-syntax">F</span><span class="plain-syntax">)) </span><span class="identifier-syntax">BinaryInter::read</span><span class="plain-syntax">(</span><span class="identifier-syntax">step</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">ephemera</span><span class="plain-syntax">.</span><span class="element-syntax">tree</span><span class="plain-syntax">, </span><span class="identifier-syntax">F</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">else</span><span class="plain-syntax"> </span><span class="identifier-syntax">TextualInter::read</span><span class="plain-syntax">(</span><span class="identifier-syntax">step</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">ephemera</span><span class="plain-syntax">.</span><span class="element-syntax">tree</span><span class="plain-syntax">, </span><span class="identifier-syntax">F</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP3" class="paragraph-anchor"></a><b>&#167;3. Move.</b></p>

<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="function-syntax">SimpleStages::run_move_stage</span><button class="popup" onclick="togglePopup('usagePopup3')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup3">Usage of <span class="code-font"><span class="function-syntax">SimpleStages::run_move_stage</span></span>:<br/><a href="2-rmss.html#SP1">&#167;1</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">pipeline_step</span><span class="plain-syntax"> *</span><span class="identifier-syntax">step</span><span class="plain-syntax">) {</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">match_results</span><span class="plain-syntax"> </span><span class="identifier-syntax">mr</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Regexp::create_mr</span><span class="plain-syntax">();</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">inter_package</span><span class="plain-syntax"> *</span><span class="identifier-syntax">pack</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">Regexp::match</span><span class="plain-syntax">(&amp;</span><span class="identifier-syntax">mr</span><span class="plain-syntax">, </span><span class="identifier-syntax">step</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">step_argument</span><span class="plain-syntax">, </span><span class="identifier-syntax">U</span><span class="string-syntax">"(%d):(%c+)"</span><span class="plain-syntax">)) {</span>
<span class="plain-syntax">        </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">from_rep</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Str::atoi</span><span class="plain-syntax">(</span><span class="identifier-syntax">mr</span><span class="plain-syntax">.</span><span class="identifier-syntax">exp</span><span class="plain-syntax">[0], </span><span class="constant-syntax">0</span><span class="plain-syntax">);</span>
<span class="plain-syntax">        </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">step</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">ephemera</span><span class="plain-syntax">.</span><span class="element-syntax">pipeline</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">ephemera</span><span class="plain-syntax">.</span><span class="element-syntax">trees</span><span class="plain-syntax">[</span><span class="identifier-syntax">from_rep</span><span class="plain-syntax">] == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) {</span>
<span class="plain-syntax">            </span><a href="2-pe.html#SP2" class="function-link"><span class="function-syntax">PipelineErrors::error_with</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">step</span><span class="plain-syntax">, </span><span class="string-syntax">"there is no Inter tree in slot %S"</span><span class="plain-syntax">, </span><span class="identifier-syntax">mr</span><span class="plain-syntax">.</span><span class="identifier-syntax">exp</span><span class="plain-syntax">[0]);</span>
<span class="plain-syntax">            </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax">        }</span>
<span class="plain-syntax">        </span><span class="identifier-syntax">pack</span><span class="plain-syntax"> = </span><span class="identifier-syntax">InterPackage::from_URL</span><span class="plain-syntax">(</span>
<span class="plain-syntax">            </span><span class="identifier-syntax">step</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">ephemera</span><span class="plain-syntax">.</span><span class="element-syntax">pipeline</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">ephemera</span><span class="plain-syntax">.</span><span class="element-syntax">trees</span><span class="plain-syntax">[</span><span class="identifier-syntax">from_rep</span><span class="plain-syntax">], </span><span class="identifier-syntax">mr</span><span class="plain-syntax">.</span><span class="identifier-syntax">exp</span><span class="plain-syntax">[1]);</span>
<span class="plain-syntax">        </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">pack</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) {</span>
<span class="plain-syntax">            </span><a href="2-pe.html#SP2" class="function-link"><span class="function-syntax">PipelineErrors::error_with</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">step</span><span class="plain-syntax">, </span><span class="string-syntax">"that tree has no such package as '%S'"</span><span class="plain-syntax">, </span><span class="identifier-syntax">mr</span><span class="plain-syntax">.</span><span class="identifier-syntax">exp</span><span class="plain-syntax">[1]);</span>
<span class="plain-syntax">            </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax">        }</span>
<span class="plain-syntax">    } </span><span class="reserved-syntax">else</span><span class="plain-syntax"> {</span>
<span class="plain-syntax">        </span><a href="2-pe.html#SP2" class="function-link"><span class="function-syntax">PipelineErrors::error_with</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">step</span><span class="plain-syntax">,</span>
<span class="plain-syntax">            </span><span class="string-syntax">"destination should take the form 'N:URL', not '%S'"</span><span class="plain-syntax">, </span><span class="identifier-syntax">mr</span><span class="plain-syntax">.</span><span class="identifier-syntax">exp</span><span class="plain-syntax">[1]);</span>
<span class="plain-syntax">        </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax">    }</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">Regexp::dispose_of</span><span class="plain-syntax">(&amp;</span><span class="identifier-syntax">mr</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">Transmigration::move</span><span class="plain-syntax">(</span><span class="identifier-syntax">pack</span><span class="plain-syntax">, </span><span class="identifier-syntax">LargeScale::main_package</span><span class="plain-syntax">(</span><span class="identifier-syntax">step</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">ephemera</span><span class="plain-syntax">.</span><span class="element-syntax">tree</span><span class="plain-syntax">), </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP4" class="paragraph-anchor"></a><b>&#167;4. Stop.</b>The "stop" stage is special, in that it always returns false, thus stopping
the pipeline:
</p>

<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="function-syntax">SimpleStages::run_stop_stage</span><button class="popup" onclick="togglePopup('usagePopup4')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup4">Usage of <span class="code-font"><span class="function-syntax">SimpleStages::run_stop_stage</span></span>:<br/><a href="2-rmss.html#SP1">&#167;1</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">pipeline_step</span><span class="plain-syntax"> *</span><span class="identifier-syntax">step</span><span class="plain-syntax">) {</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
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